1. Field of the Invention
The present invention relates to a heater used for heating a substrate, such as a semiconductor wafer and a liquid crystal substrate, and a method of manufacturing the same.
2. Description of the Related Art
In general, a heater which heats a semiconductor wafer and the like at least includes a substrate having a heating surface on which an object to be heated, such as a wafer, is placed and a resistant heater element embedded in this substrate.
This heater is manufactured by discriminating a peripheral shape of the resistant heater element, determining a central axis of the resistant heater element using the peripheral shape as a reference and allowing the central axis of the resistant heater element and a central axis of the substrate to be the same axis. A peripheral portion of the resistant heater element can be discriminated by use of X-ray photography or the like in a case where the resistant heater element is embedded within the substrate. Alternatively, the peripheral portion thereof can be discriminated by use of an image processing technology or the like in a case where the resistant heater element is on a surface portion of the substrate.
Moreover, heat uniformity of the heater is conventionally evaluated once the heater is a finished body capable of electrical connection.
In recent years, regarding a heater which heats a semiconductor wafer or the like, since the thermal uniformity thereof directly affects a yield of an element, the requirements for thermal uniformity on the heating surface of the heater have become increasingly strict. It is required to set the thermal uniformity to t° C.±1.0% or less for a predetermined temperature (t° C.) and to minimize the fluctuation range of temperature for a predetermined temperature distribution.
However, conventionally, since thermal uniformity has been evaluated for the finished body after the heater has been brought to completion, the heat uniformity has never been confirmed in the middle of the manufacturing process thereof. Moreover, the size of the finished body is already determined based on the relationship between the heater and the semiconductor manufacturing apparatus incorporating the heater built therein. Thus, it was not easily possible to change the shape of the heater in order to improve thermal uniformity and the like.